Purification of by-product ammonia



Patented Feb. 9, 1932 UNITED STATES PATENT OFFICE ALPHONS O. JAEGER, OF GRAFTON, PENNSYLVANIA, ASSIGNOR TO THE SELDEN GOM- PANY, OF PITTEBURGH, PENNSYLVANIA, A CORPORATION OF DELAWARE PURIFICATION OF BY-PRODUCT AMMONIA No Drawing.

This invention relates to the purification or ammonia produced as a byproduct of the nun'uifacture of coke or similar products of the destructive distillation of carbonaceous material. This ammonia is frequently referred to as coal tar ammonia and is almost invariably quite impure, being contaminated with organic compounds such as phenols, heterocyclic bases, such as pyridines, sulfur compounds, both organic and inorganic, such as hydrogen sulfide, and the like. The purification o'l' by-product ammonia has presented great difliculties in the past and has seriously limited its field of utility as its impurities must be removed or transformed into harmless compounds to permit the use of the ammonia for many industrial purposes.

The present invention removes the organic impurities of by-product ammonia by a selective catalytic oxidation in the presence of catalysts which, at the reaction temperature used, favor the oxidation of organic and other impurities but do not eiiect notable oxidation of the ammonia itself. It has been found that practically all contact masses which have been used in vapor phase organic oxdiations may be utilized in the present invention as at tenn'ieratures which are high enouuh to effect total combustion of the organic impurities, ammonia is relatively stable toward oxidation.

The present invention includes the use of any type of oxidation catalyst, whether stahi izcd or imstabilizcd. Among the Well known mistabilized contact masses for organic oxidations may be mentioned the oxides oi" various elements, such as silver, zinc, cad; mium, aliuninum, thorium. zirconium, titanium, tin, cerium, lead, manganese, and particularly metal elements of the fifth, sixth and th groups of the periodic system. such as vanadium. chron'iiun'l, tantalum, molybdenum, turr -ten. uranium, iron. nickel, cobalt, manganese, et Other compounds than the oxides have, oi" course, been used, such as, for example, salts-1 o? the metal acids of the fifth and sixth groups, and the like. Platium and pallzulium. usually in the Form of linely divided elements, have also been used oxidation catalysts and can be used in the present Application filed March 15, 1929. Serial No. 347,449.

invention where the ammonia is free from poisons of platinum.

It is found, for example, that stabilized contact masses frequently give advantageous results. These stabilized catalysts have noncatalytic compounds 01 the alkali i'orming metals, that is to say alkali metals, alkaline earth metals, and some of the more basic earth metals, associated with them. These compounds may be strongly alkaline as hydroxides, oxides, carbonates, or cyanides of the alkali-forming metals or they may be nonalhaline, neutral salts, or even acid salts. These compounds appear to stabilize the action of the contact mass and for this reason will be referred to throughout the specification as stabilizers. The stabilization of the oxidation catalyst frequently permits the use of higher temperatures without damage to the ammonia and in other cases may result in the oxidation of certain organic compounds to valuable intermediate products. Thus, for example, phenols may be oxidized to maleic acid, and the like. The choice between stabilized and unstabilized catalysts and between diil'erent stabilized catalysts, will, of course, depend on whether it is desired to completely burn all organic impurities present or whether it is worth while to transform them into valuable intermediate oxidation products, which can be recovered in many cases. Where complete combustion is desired and considerable amounts of nitrogenous heterocyclic compounds are present, strongly alkaline sta bilizers are of advantage as they appear to favor the total combustion of such compounds as pyridine. Where it is desired to oxidize certain of the organic impurities to intermediate products, it is usually preferable to use non-alkaline stabilizers and in some cases it is advantageous to use acid stabilizers, such as, for example, bisul'fates of. the alkali-forming metals.

In addition to stabilizers it has been found that many contact masses can be improved by the addition of catalytic components which are not specific oxidation catalysts, such as, for example, components which have dehydrogenating, dehydrating, decarboxylating, and similar properties. In the following examples certain specific substances will be described which function in this manner.

out the specification as stabilizer promoters,

' it being clearly understood that theinvention is in no sense limited to any theory of action of the stabilizer promoters.

A class of eliective contactmasses for carrying out the present invention are the socalled uermutogenetic contact masses which includes base exchange bodies, silicone or' non-silicious, two-component or multi-component, such as, for example, zeolites and rtheir derivatives, and, the products obtained by leaching them with dilutemineral acids. All of-these products are highlyporous and -producecontact masses. in which 1 the catalytically active components are most intimate ly distributed or dispersed andin the case of permutogenetic bodies containing chemically combined components they :are .molecularly dispersed. .The advantageous .physicalstructure voflthe permutogenetic contactimasses, and especially diluted permutogenetic contact-masses, render them among themost efiective forthepu'rification of ammonia. V

The use of stabilized catalysts generally .hasbeen describedabroadly for organic oxitdations'inmy prior Patent No. 1,709,853, dated April 23, :1929,the use of three-com- ;ponent zeolites for organic oxidations has :been described-in my prior PatentNo. 1,722,- .297:dated July-30,-1929' and, finally, the use -.of. non-silicious .baseexchangebodies for organic oxidations I has been broadly described in -my prior Patent No. 1,735,763 dated.November1l2,?1929. The present invention isin'part a continuationof the three above referred to-patents. The use ofitwocomponent zeolites has been described :for organiooxidationsin my Patent No. 1,694,- ;122,:issued December 14, 1928. .It-should be understood that any suitable oxidation cat-alystsdescribed inthe foregoing patentsmay be used for the present invention. As is well known to' zeolite chemists,: and described :in ;my :prior patents abovereferred to, base exchange rbodies consist of an exchangeable base- Which can be reversibly exchanged for other: bases by 5 treatment with salt solutions and -a non-exchangeable nucleus, the com- ;ponents of which can not be so exchanged and-are therefore-said'to be present in nonexchangeable .torm.

In addition to the permutogenetic contact masses referred toin "the above ,mentioned .applications,which arebase exchange bodies orttheir salt-like. derivatives, highly effective contact masses may be produced by leaching base exchange bodies .or their derivatives with dilute mineral"acids,-such as, forexample,"hydrochloric orinitric acid. The leaching first removes exchangeable bases and then gradually removes the more basic portion of the nucleus base exchange body. A I series of products are obtained in which part of the exchangeable. bases may be retained or in which the leaching may have been carried toithe point otcomplete elimination of the exchangeable bases and part or complete elimination of the more basic portion of the base exchangenucleus: \Nhen the leaching is carried. to completionleaving only the acid constituents of the nucleus the product is a complex silicio acid, in the case of zeolites and usually is not itself catalytically active but it retains the high porosity characteristicofrbase exchange .body and forms a most efiective carrier for .the catalytically active elements. .1 do notclaim here broadly the oxidation of organic compounds by means of leached permutogenetic bodies, this forming the subjectinatter of my co-pending application, Serial No. 294,597, filed July 21,1928. 1 .Itshould be understood that in the present invention contact masses are not limited to those-which: are highly ellective for the oxillation of organic compounds to intermediate products .and which normally contain as. their" main catalytically active ingredients one or more ofthe metal elementsot the-fifth vand sixth groups of the periodicsystem. On the :contrary contact masses which do not contain metal elements of the fifth and sixth groups of theper-iodic system and which may contain -metal elements of the seventh 0r 'eighth orother groupsof the periodic sys-- tem are 'veryreifective and any contact mass which .favorsthe oxidation of organic compounds .andother impurities may be' used in the present invention. f

Incarrying out the process of this inven- Ltion (the impure .by-product ammonia is ad- 'mi-xed with .a suitable oxidizing gas, which .rnay, for example, be air or other gas containingoxygen and is passed over-the con- -lJHCt-HIHSStO etlect suitable combustion of or- 3 gani'c or other impurities. It is advantageous {in many'cases to operate with a considerable .excess ofoxidizinggas, althoughthe invenition is in no sense limited to a process em- ..bodyingthis Ifeaturc. An almost total combastion of or anic im urities takes lace and e P p the ammonia obtained canbe used, if necessary, after suitable-separation from the gas stream, for any of theindustrial purposes which-normally require highly pure ammoi ;nia. and which in'the past have been largely .restricted to synthetic ammonia, which is frequently of considerably higher cost. The

contaminated with large amounts of impurities, can be purified catalytically, it is sometimes desirable to submit the ammonia to partial preliminary purificaton by other well lmown methods and then to finally purify it by selective oxidation. In other words, the present invention can be applied not only to crude by-product ammonia but also to ammonias which have been partly refined although, of course, unfit for many industrial purposes. The choice of whether the crude by-product ammonia is to be catalytically purified or whether partial purification by other methoc s is to precede the catalytic purification is primarily an economic question and depends on whether the preliminary purification can be effected more cheaply or can result in the recovery of by-products in a form in which. they could not be recovered if the crude ammonia were catalytically purified. In every case, of course, the skilled chemist will apply the present invention to a crude or partly purified ammonia of the grade giving the best results in any particular installation.

The invention will be described in greater detail in connection with a few specific examples which represent a number of modifications of the invention which, however, is in no sense limited to the exact details set forth in the examples, which are intended only as illustrations of typical modifications.

Emamplc 1 A contact mass is prepared by imprcgnatiupg fragn'ients of fire brick with a solution containing equi-molecular mixture of copper and ferric nitrate to which from 2 to 5% of bismuth nitrate has been added. After im-- proanating the fire brick granules, they are calcined with air at about 650 Cruntil the nitrates have been transformed into the cor responding oxides. The contact mass is then filled into a converter and a mixture of byproduct ammonia and air is passed over at from 300-500 L, preferably at about 400 C. The organic and sulfur containing impurities are burned out or transformed into sulfur trioxide, and the purified ammonia may be removed from the exhaust gases by washing in cold water or by any other suitable means. In this contact mass bismiu'h oxide, a dihydrogenation catalyst, is a nonspecific catalytic component.

It should be noted that the above contact mass, which is a well known annnonia oxidation contact mass, at the lower tempo ature used no longer favors the oxidation of ammonia but permits purification by combustion of the impurities without substantially attacking the ammonia. Similarly, other known ammonia oxidation contact masses can be used under reaction conditions such as those described above.

Ewample 2 Fragments of ilmenite or an artificial mixture of iron oxide and titanium oxide, a catalyst favoring both dehydration and dehydrogenation containing approximately the same proportions of the oxides are filled into a converter and a mixture ofby-product ammonia and air containing a considerable excess of oxygen over that theoretically required to,

burn out the impurities present, is passed over the contact mass at 300-500 (1., preterably at about 400 C. The impurities are burned and the purified ammonia may be recovered in the usual manner. 4

E mample 3 An artificial carrier is made by impregnating parts of k1ese1guhr or silicate rock with a concentrated solution containing 25.,

The contact mass after this treatment is suitablefor many specific catalytic oxidations. Thus for example, ammonia recovered from coal tar distillation and containing small amounts of organic compounds as impurities, can be purified by passing the vapors;

of ammonia mixed with air in proportions of 1:10 over the above contact mass at temperatures from 400 to 460 C. Instead of cadmiate solution other metallates used.

Example 4 A natural or artificial zeolite consisting of a sodium aluminum polysilicate is treated with an aqueous solution of potassium ch1oride, rubidium chloride, caesium chloride or magnesium sulfate, or mixtures, in order to remove the sodium by base exchange. The zeolite is then dried and sprayed with solutions or suspensions of the oxy metal acids of the fifth group of the periodic system of their ammonium or metal salts, such as am monium vanadate, iron vanadate, etc. The product is then calcined and if necessary, treated with mineral acid vapors or dilute; mineral acids and constitute good catalysts for the catalytic purification of coal tar ammonia when the latter mixed with air is passed over the catalyst at 370-450 C.

In the above contact mass the alumina in the Zeolite is a dehydration catalyst while iron compounds are primarily dehydrogenation catalysts, although they exert a slight dehydrating action. Both substances serve as stabilizer promoters in the reaction.

may be .Ehaample V solved in '8.7 parts of 100% KOH dissolved '-w'ith:150 parts of Water and warmed to about 80 C. 7.5 partsof ferric chloride dissolved in 100 parts of Water are then added-andthe light brown precipitate thus obtained'is-fil- ".tere'd and'thoroughly Washed. The Wet precipitate obtained is'suspended in' a solution :containing =7 parts of potassium sulfate in 250 parts of-Water and isused to impregnate 200'zvolumes of pea-sized "which are then calcined.

The contactmass .is filled into a converter andvapors of by-product ammonia mixed With air are passed over the contact mass at 300-50? (3., the impurities" being complete zlyattacked, andpurified ammonia recovered in the usualmanner.

pumice fragments :The contact mass described in this example isone which is suited for the catalyticpurirfication of crude anthracenej It should be :noted that'in general contact masses which 25 are suitable for the catalytic purification of 'crude anthracene are also suitable for use in the present invention under the reaction conditions. given.

Instead of iron molybdate :molybdenum oxide-or other molybdates,suchas silver or copper molybdates, or acids or salts oftung- :sten, chromium or uranium may be used. In

iplace ofthe stabilizer used potassium bromide, potassium'cyanide,potassium chloride,

=sod(i1um' sulfate or other-=stabilizers may be :use i Example 6 12 parts of vanadicacid areltreated'With do suflicient 2 N. potassium hydroxide solution r so that not only is all-01611118 V dissolvedin the form of potassium vanadate, but an excess of '14 parts of 100% "KOH remains. .A mixture of 1120 parts of coniminuted nated with the .above described solution. The second solution is prepared by reducing lOzparts of vanad-ic acid to vanadyl sulfate in the usual manner and neutralizing the excess 4 sulfuric "acid with 2 N. potassium hydroxide solution; y

Solution 2 and suspension 1 are 'then fkneaded together thoroughlyand dried at temperatures underl00 -C. 'The product is -a-'base exchange body c'ontaining K' 'O, V 0

and -20.1. The large lumps areflbroken into small fragmentswvhereby a good, e'liicient catalyst is obtainedfor-the catalytic oxidation oftar'ammonia. "Tar ammonia mixed with air, a large excess of air in proportion quartz and parts of kieselguhr is impregmonia is purified by selective oxidation of 10 .parts of 'mol-ybdenumcoxide are 'tldish Qrgamc n I v Emampl 7 The-following solutions are prepared 1. parts of nickel nitrate containing-6 .mols of Waterofcrystallization are dissolved in 200 parts of Water and sufiicient 25% ammonia is added until a clear solution of the nickel ammonium nitrate is obtained. Nickel is a dehydrogenation catalyst.

2. a parts of freshlyprecipitated aluminumhydroxide are stirred into a-slurry'with '50-parts of Water and. are then heated with a sufli-cient 10 N. sodium or potassium hydroxide'solution to just form a'cl-ea'r solution of the corresponding aluminatea;

3. 10 parts of chromiumnitrate with-9 mols of water of crystallization'are dissolved in 150 parts of water and thentreated with 5-10'N. potassium orsodium hydroxide solution until the corresponding chromite is formed. Chromic oxide isprimarily a dehydration catalyst.

. 4. 8 parts of zinc nitrate containing6 mols of water of crystallization are dissolved in partsof Water and treated With just sufficient 5-10 N. sodium hydroxide solution to of Water ofcrystallization are dissolved in 150 parts ofwater. Zirconium oxide is both a dehydration and dehyrogenation catalyst, having almost equal'properties foreach.

7 '16 parts of titanium, nitrate are dissolved in 160parts of waten' Solutions 1,2, 3 and 4 are mixed together copper or iron ores may also be used. 7

To the suspension, amixture ofthe solutions of5, 6, and 7 is added With vigorous agitation. A gelatinous reaction product forms and if it is strongly alkaline to phenol- -phthalein, the excess of alkali may be neutralized with. 5% nitric acid until justneutral or alkaline to phenolphthalein whereby the yield of the base exchange body can be increased.

The product is dried attemperatures below 100 C. and is a'baseexchan e body containing sodium, potassium, ammonium, nickel, aluminum, chromium, zinc,z1rcon1um, and

"titanium. When broken into fragments and calcined at 400 C. it can be used as contact mass for the purificationof by-product ammonia under the reaction conditions described in the foregoing examples.

The contact mass of this example is an excellent contact mass for the catalytic oxidation of crude anthracene' and is another ex- 1 ample of a contact mass of this type which is suitable for the process of the present mvention.

Example 8 18 parts of vanadium pentoxide are suspended in 300 parts of water rendered weakly acid with concentrated sulfuric acid and reduced to the blue vanadyl sulfate by means of sulfur dioxide in the usual manner. The solution boiled and concentrated to 150 parts of water. One-third of the vanadyl sulfate solution treated with 10 N. potassium hydroxide solution to transform it into the colleebrowu potassium vanadite, whlch is then mixed with a solution containing 10 parts of aluminum oxide transformed into potassium aluminate by a N. potassium hydroxide solution. 100 parts of lnfusorla-l earth are thoroughly mixed with the vanadite-alrmiinate solution and the remaining two-thirds of the vanadyl sulfate solution 1s hen introduced with vigorous agitatlon. The final product should remain strongly alhaline to litmus.

he product is pressed, dried as usual under 100 0., broken into fragments, and then subjected to base exchange by digesting 1t with a 5% solution of ferric nitrate in order to substitute a maximum of alkali by ferric iron. The product, after base exchange, is filled into a converter and the vapors of byproduct ammonia mixed with air are passed over it at 3ti0--Cl50 G, the organic impurltles being oxidized to carbon dioxide and water with the production of some elementary nitrogen.

E'azamplc .9

Pea sized quartz fragments are treated with 20% solution of hydrofluoric acid 1n or der to etch their surface. On these carrier fragments is formed a base exchange body containing platinum, the amount of coatrng being about by volume of the carrier fragments.

lnstead of forming the base exchange body in situ on fragments the finished base exchange body may be pulverized and afterwards coated on the carrier fragments with the help of adhesive substances such as waterh' gSO HOT-l, NaOH, and the like.

i The base exchange body is prepared as follows:

5 parts of AM); are transformed into potassium aluminate using a 5 N. potassium hydroxide solution. After the formation of the potassium aluminate an excess of alkali amounting to 10-15% should be present. l parts of lihltCl, in the form of 10% solution are then added to the aluminate solution under vigorous agitation. 22 parts of FeflsO 3 9 aq. are dissolved in 200 parts of water and are then added gradually with strong agitation, care being taken that the resulting reaction product remains slightly alkaline or neutral to phenolphthalein.

The base exchange body obtained containing aluminum, iron and platinum in non exchangeable form is freed from the mother liquor by pressing and dried.

Instead of an undiluted base exchange body a diluted base exchange body may be used, especially when using powdered quartz or material rich in silica such as colloidal SiO ,lIieselg11l11' and the like, as diluents, and is an effective catalyst for the selective purification of tar ammonia in order to burn out the organic impurities and transform the inorganic impurities such as sulphur to nonvolatile compounds whereby ammonia of a high purity is obtained. Tar ammonia is mixed with air in such a ratio that the excess of oxygen based on the amount of impurities is suiiicient to be able to burn or transform all the impurities. The best working temperatures are between 320 and 420 C.

Ewample 10 Three mixtures are prepared as follows:

(1) 210 to 250 parts of potassium or sodium water glass of 33 B6. are diluted with to volumes of water and mixed with kieselguhr or other material rich in SiO such as glaucosil (the acid treated residue of greensant), the diluents being impregnated with it of iron oxide, nickel oxide, copper oxide, cobalt oxide, aluminum oxide, or a mixture. The amount of diluents added should be such that the suspension is just stirrable.

(2) 18 parts of V 0 are dissolved in just suflicient 10-20% caustic potash or caustic soda solution so that potassium or sodium vanadate is obtained.

(3) 18 parts of V 0 are'reduced with sulfur dioxide in aqueous suspension in the usual way to form the blue vanadyl sulfate, about 200 to 300 parts of water being needed. The excess S0 is removed by boiling.

Mixtures 1 and 2 are poured together and Solution #3 is permitted to flow in with vigorous agitation, care being taken that the reaction mixture remains at least alkaline to litmus. The alkalinity can be adjusted by slight additions of N. potassium hydroxide solution, if necessary. A dirty gray-blue gel results which is filtered with suction, washed with a little water andthen dried and constitutes a three component base exchange body containing tetravalent and pentavalent vanadium in non-exchangeable form and having materials rich in SiO finely distributed throughout its framework.

The contact mass is filled into a converter and a mixture of byproduct ammonia and air, the amount of air providing a large excess of oxygen over that theoretically required for the total combustion of the. organic substances present and for the conversion of sulfur compounds to S0 is passed over the con tactmass at 420-500 (3., a very pure ammonia being obtained and recovered in the usual manner.

Example 1 1. p

A two-component zeolite of the same em-.

pirical chemical composition as that in the fOIB OIII exam le is re aredb transform- P mg tne vanadyl sulfate solution into colleebrown potassium vanadite by means of 10 N Example 12 Quartz fragments about the size of a pea are treated with about 20% solution of hydroflouric acid in order to rou hen the surface of the quartz fragments. an these carrier fragments a three component base exchange body containing platinum is formed, the amount of coating preferably being about 10% of the volume, of the carrier fragments. '5 Instead of forming the base exchange body in situ on the fragments the finished three component base exchange body may be pulverized and coated afterwards on the carrier fragments with the help of adhesive substances such as watergloss, MgSO KOH, NaOH- and the like.

. I The base exchange body is prepared in the 1 following way: V a 7 1'. '2 parts of A1 0 are transformed into potassium aluminate using N. potassium'hydroxide solution.

2. 40 parts of sodium waterglass solution of about 36 B. are diluted with five vol-' umes of water. 7

3. 4 parts of H PtCl are to 5% solution.

4. 15parts of Fe (S0 3 9 aq. are dissolved in about 150 parts of water.

. The solutions 1 and 2 are poured together and then the mixture of the solutions 3 and 4 is poured in with vigorous agitation, care being taken that the resulting three component base exchange body, containing aluminum SiO' iron and platinum innon-exchangeable form, remains alkaline to litmus or preferably neutral to phenolphthalein.

The base exchange body obtained is freed from the mother liquor by pressing, and then dried. .Before using this material it .may advantageously be hydrated by trickling water over it until the Water which drains ofi does not contain appreciable amounts of salts. Instead-of using an undiluted base exchange body a diluted base exchange body prepared in a 2 may be prepared, particularly one usin pow dered quartz,si1icates orother materia rich 7 in silica, such as colloidal SiO kieselguhr,

and the like, as diluents. A contact mass prepared with such a multi-component diluted base exchange body is an effective contact mass for the catalytic purification of. coal tar ammonia, crude naphthalene and the like, many of the impurities being selectively burned out during the reaction as described informer examples. N 7

Example 13 ,22 parts of basic copper carbonate are dis- M solved in the form of a cuprammonium compound. 10.2 parts of freshly precipitated aluminum hydroxide are dissolved in sufiicient 2 N. sodium hydroxide solution to form a clear sodiiun aluminate solution. 24 parts of copper nitrate containing 3 mols of Water are dissolved in parts of water. The cuprammonium carbonate and the aluminate solution are then mixed together and the copper nitrate solution poured in with vigorous agitation. A gelatinous product is formed which is neutral or slightly alkaline to phenolphthalein, which constitutes a non silicious base exchange body containing sodium, copper v and aluminum. The gel is pressed and dried at temperatures under 100 C. and then hydrated with water. Thereupon the non-silicious base exchange body is placed on a nutch filter and carefully leached with 25% sulfuric acid, 250-500 parts of the diluted acid being gradually trickled over the base exchange body. If desired part of the exchangeable alkali may be replaced by such bases as iron, cobalt,manganese, chromium,

titanium, zirconium, copper or thorium by trickling 540% solutions of the corresponding' salts over the base exchange body. Thereupon the product is leached to remove exchangeable alkali.

Salt-like bodies of the base exchange body mayalso be formed as has been described abovein the foregoing examples and then leached.

The contact masses after leaching are kneaded with 1520% by Weight of potassium sulfate, potassiumnitrate, potassium chloride, potassium hydroxide, potassium carbonate, potassium phosphate or other alkali metal compounds in the form of water'solutions or water 'lass solutions ma be used'as cementing agents. The kneaded products are formed into suitable pellets and calcined at temperatures above' lOO" G. These contact masses are filled into a'converter' and by-product ammonia mixed with air, the latter preferably in large excess over that theoretically required for combustion of organic impurities present, is passed overthe contact mass at 380*.450 0. Theorganic impurities are entirely burned out or transformed into water soluble compounds. The ammonia is recorerod in the usual manner.

in the claims the term permutogenetic ctwors base exchange bodies, silicious or nonsilicious, the products obtained by the acid l ach or" these base exchange bodies and the salt-litre bodies obtained by the reaction ct these base exchange bodies with compounds the acid radicals of which are capable of reacting with the base exchange bodies to produce products which show most oi? the properties of salts. WVhen so used in the claims, the term permutogenetic will have no other meaning.

llhis application is in part a continuation of my prior applications, Serial Nos. 196,393, tiled June El, 1927 now Patent No, 1,709,853; 211,638, tiled August 8, 1927 now Patent No. 1,735,113; 215 759., tiled August 26, 1927 new Patent lio. 1,122,297 and co-pending application 29-41:,59i', tiled July 21, 19:28.

ll hat is claimed as new is:

1.. A method of purifying by-product ammonia containing organic impurities which comprises passing the lay-product ammonia admixed with an oxygen containing gas over an ott'dation contact mass at temperatures at which the organic impurities are oxidized and the ammonia substantially unattached.

A method of purifying lay-product ammonia containing organic impurities which comprises passing the ammonia admixed with an oxygen containing gas, the amount of oxygen being in excess of that theoretically required for the complete oxidation of the impurities over an oxidation contact mass at temperatures at which the organic impurities are oxidized and the ammonia is substantially unattached.

A method oi purifying lay-product ammonia which comprises passing the lay-prod not ammonia admixed with an oxygen containing gas over an oxidation contact mass containing at least one compound of an ele- :ment contained in the groups which includes alkali metals, alkaline earth metals and earth metals whose oxides are not reducible by hydrogen at temperatures at which the impurities are oxidized and the ammonia is substantially una ttaclze d.

ti. A method according to claim 1 in which the contact mass contains at least one perinutogenetic body.

A method according to claim 1 in which the contact mass contains at least one diluted perniutogcnetic body.

(3. A method according to claim 1 in which the contact mass contains at least one permutogenetic body, at least one of the catalyticully etlective components of the contact mass being combined in or with the permutogenetic body in non-exchangeable form.

7'. A method according to claim 1 in which the contact mass contains at least one zeolite.

8. A method according to claim 1 in which the contact mass contains at least one diluted zeolite.

9. A method according to claim 1 in which the reaction is carried out at temperatures between 300-500 C.

10. A method according to claim 1 in which the contact mass contains at least one nonspecific catalyst.

11. A method according to claim 3 in which the contact mass contains at least one nonspecific catalyst.

12. A method according to claim 1 in which the contact mass contains at least one oxide of the metal falling within the group copper, iron, bismuth.

13. A method of purifying icy-product ammonia which comprises passing it admixed with an oxygen containing gas over an ammonia oxidation contact mass, containing at least one oxide of the metal included in the group copper, iron, the contact mass also con taining relatively smaller amount of bismuth oxide, at temperatures at which the impurities are oxidized, but the ammonia remains substantially unattached.

Signed at Pittsburgh, Pennsylvania this 13th day of March, 1929.

ALPI-IONS O. JAEGER. 

